Large-scale water purification and desalination

ABSTRACT

Embodiments of the invention provide systems and methods for water purification and desalination. The systems have a preheater, a degasser, multiple evaporation chambers with demisters, heat pipes, and a control system, wherein the control system permits continuous operation of the purification and desalination system without requiring user intervention or cleaning. The system is capable of recovering heat from each distillation stage, while removing, from a contaminated water sample, a plurality of contaminant types including: microbiological contaminants, radiological contaminants, metals, salts, volatile organics, and non-volatile organics.

This application claims priority to U.S. Provisional Patent ApplicationNo. 61/097,835, filed Sep. 17, 2008, and the entire disclosure of thatapplication is incorporated herein by reference. This invention relatesto the field of water purification and desalination. In particular,embodiments of the invention relate to systems and methods of removingessentially all of a broad spectrum of impurities from water in anautomated process that requires minimal cleaning or maintenance duringthe course of several months to several years, with relatively highyields of product water per unit of input water and ultra-low energyrequirements.

BACKGROUND

Water purification technology is rapidly becoming an essential aspect ofmodern life as conventional water resources become increasingly scarce,municipal distribution systems for potable water deteriorate with age,and increased water usage depletes wells and reservoirs, causing salinewater contamination. Additionally, further contamination of watersources is occurring from a variety of activities, which include, forexample, intensive agriculture, gasoline additives, and heavy toxicmetals. These issues are leading to increasing and objectionable levelsof germs, bacteria, salts, MTBE, chlorates, perchlorates, arsenic,mercury, and even the chemicals used to disinfect potable water, in thewater system.

Furthermore, even though almost three fourths of the earth is covered byoceans, fresh water resources are limited to some 3% of all planetarywater and they are becoming scarcer as a result of population growth andglobal warming. Approximately 69% of all fresh water is held in ice capsand glaciers which, with increased global melting become unrecoverable,so less than 1% is actually available and most of that (over 90%) isground water in aquifers that are being progressively contaminated byhuman activities and saline incursions. Thus, there is an urgent needfor technology that can turn saline water, including seawater and brine,into fresh water, while removing a broad range of contaminants.

Conventional desalination and water treatment technologies, such asreverse osmosis (RO) filtration thermal distillation systems likemultiple-effect distillation (MED), multiple-stage flash distillation(MSF), or vapor compression distillation (VC) are rarely able to handlethe diverse range of water contaminants found in saline environments.Additionally, even though they are commercially available, they oftenrequire multiple treatment stages or combination of various technologiesto achieve acceptable water quality. RO systems suffer from therequirement of high-water pressures as the saline content increaseswhich render them increasingly expensive in commercial desalination, andthey commonly waste more than 30% of the incoming feed water, makingthem progressively less attractive when water is scarce. Lessconventional technologies, such as ultraviolet (UV) light irradiation orozone treatment, can be effective against viruses and bacteria, butseldom remove other contaminants, such as dissolved gases, salts,hydrocarbons, and insoluble solids. Additionally, most distillationtechnologies, while they may be superior at removing a subset ofcontaminants are frequently unable to handle all types of contaminants.

Because commercial desalination plants are normally complex engineeringprojects that require one to three years of construction, they normallyare capital intensive and difficult to move from one place to another.Their complexity and reliance on multiple technologies also make themprone to high maintenance costs. Thus, because RO plants are designed tooperate continuously under steady pressure and flow conditions, largepressure fluctuations or power interruptions can damage the membranes,which are expensive to replace; that technology requires extensivepre-treatment of the incoming feed water to prevent fouling of the ROmembrane. Thermal distillation systems frequently rely on vacuum toincrease water recovery by extracting increasing steam with a givenamount of thermal energy; however, vacuum systems in large-scale systemsare troublesome because of leaks and require mechanical reinforcement.Thermal systems also rely on heat exchangers to recover some of the heatof condensation, but heat exchangers are prone to fouling and scaleformation and require frequent maintenance.

Accordingly, sophisticated distillation systems that are continuous andself-cleaning, that resist corrosion, that are portable and compact andrecover a major fraction of the input water, and that are relativelyinexpensive and low-maintenance appear as the best long-term option toresolve increasing water contamination problems and water scarcity,worldwide.

SUMMARY

Embodiments of the present invention provide an improved desalinationand water purification system. The system can include an inlet, apreheater, a degasser, multiple evaporation chambers and demisters,product condensers, a waste outlet, a product outlet, multiple heatpipes for heat transfer and recovery and a control system. The controlsystem permits operation of the purification system continuously withminimal user intervention or cleaning. The system is capable ofremoving, from a contaminated water sample, a plurality of contaminanttypes including microbiological contaminants, radiological contaminants,metals, salts, volatile organics, and non-volatile organics. Inembodiments of the system, the volume of water produced can be betweenabout 20% and about 95% of a volume of input water. The system comprisesa vertical stack arrangement of evaporation chambers, condensers, and apreheater that is compact and thus portable in the range of 1,000 to 50million gallons per day of water production.

The system can also include a flow controller for the input water. Theflow controller can include a pressure regulator, a pump, a solenoid, avalve, an aperture, and the like. The pressure regulator can maintainwater pressure between about 0 kPa and 250 kPa. (0 to 36 psi). The flowcontroller can maintain water flow at a rate of between 0.5 and 3500gallons/min. The system can include a sediment trap, a sand filter, andthe like. Also, the system can further include a shutdown control. Theshutdown control can be, for example, a manual control, a flood control,a tank capacity control, an evaporation chamber capacity control, orsimilar control device. The feedback control system can be based upon,for example, amount of water in a product water tank, flow of productwater through the product outlet, time of water flow, time of no waterflow, amount of water in the evaporation chamber, detection of a leak,evaporation chamber pressure, output water quality (total dissolvedsolids), pressure differential across evaporation chamber, evaporationchamber overflow weir float, and the like.

Also, the system can have a preheater that heats the incoming water tothe temperature required in the degasser. Water exiting the preheatercan have a temperature of at least about 96° C. The preheat tank mayhave a spiral arrangement of vanes such that incoming water circulatesseveral turns in the tank, thus providing the residence time to effectpre-heating. Incoming feed water enters the preheater tangentially, isgradually preheated by heat pipes until the required temperature isachieved, and exits the preheater through a downcomer tube that connectseither with the degasser or directly with a lower evaporation chamber ifthere is no need for degassing.

The degasser can be in a substantially vertical orientation, having anupper end and a lower end. Pre-heated water enters the degasser at itsupper end, and degassed water exits the degasser proximate to the lowerend. In the system, steam from the highest evaporation chamber can enterthe degasser proximate to the lower end, and can exit the degasserproximate to the upper end. The degasser can include a matrix adapted tofacilitate mixing of water and steam, stripping the inlet water ofessentially all organics, volatiles, and gasses by counterflowing theinlet water against an opposite directional flow of a gas in a degasser.The gas can be, for example, steam, air, nitrogen, and the like. Thematrix can include substantially spherical particles. However, thematrix can also include non-spherical particles. The matrix can includeparticles having a size selected to permit uniform packing within thedegasser. The matrix can also include particles of distinct sizes, andthe particles can be arranged in the degasser in a size gradient. Watercan exit the degasser, substantially free of organics and volatilegases.

The upper evaporation chamber can include a cylindrical or rectangulartank with a perforated bottom that accommodates multiple heat transferpipes. The upper evaporation chamber can also include a central drain,which can be a downcomer tube in fluid communication with a lowerevaporation chamber, or at the bottom of the evaporation chamber, orboth. The evaporation chamber can also include a self cleaning mediumincluding a plurality of particles, the drain having an opening, theopening having a size that does not permit the particles to pass throughthe bottom drain, the opening further having a shape that is notcomplementary to a shape of the particles. The evaporation chamber caninclude a self cleaning medium for interfering with accumulation ofprecipitates at least in an area proximate to a heated region of theevaporation chamber. The medium can include a plurality a particles. Theparticles can be substantially spherical. The particles can also includea characteristic permitting substantially continuous agitation of theparticles by boiling of water in the evaporation chamber. Thecharacteristic can be, for example, specific gravity, size, morphology,population number, and the like. The particles can have a selectedhardness, so that the hardness permits scouring of the evaporationchamber by the particles without substantially eroding the particles orthe evaporation chamber. Furthermore, the particles can be composed ofceramic, metal, glass, or stone. The particles can have a specificgravity greater than about 1.0 and less than about 8.0, or morepreferably, between about 2.0 and about 5.0.

The upper demister can be positioned proximate to an upper surface ofthe evaporation chamber. Steam from the evaporation chamber can enterthe demister under pressure. The demister can include a pressuredifferential, and the pressure differential can be no less than 125 toabout 2500 Pa. The demister can be adapted to separate clean steam fromwaste steam via either cyclonic action or by providing mechanicalbarriers to mist particles being carried by steam. The ratio of cleansteam to waste steam can be greater than about 10:1. The control systemcan adjust a parameter to regulate steam quality. Steam quality caninclude, for example, clean steam purity, ratio of clean steam to wastesteam, and the like. The parameter can include at least one parametersuch as a recess position of a clean steam outlet, a pressuredifferential across the demister, a resistance to flow of a steam inlet,a resistance to flow of a steam outlet, and the like.

Clean steam from the demister enters an upper condenser that includesvanes for imparting a circular motion to the steam, thus enhancing itsresidence time in the condenser and ensuring complete steamcondensation. The condenser tan is a cylindrical or rectangular tankwith a perforated top that accommodates multiple heat pipes. The heatpipes remove the heat of condensation of the steam and transfer suchheat either to the upper preheater or to an upper evaporation chamber.Product water can exit the product condenser through the product outlet.

Multiple stages of boiling and condensation can be provided under theupper condenser, thus recycling heat for multiple stages ofdistillation. Except for the last stage, which is the bottom evaporationchamber, each stage consists of a evaporation chamber, a demister, acondenser, and multiple heat pipes, all identical to those describedabove.

The bottom evaporation chamber is identical to the upper evaporationchamber, except that a source of heat energy is placed under it orinside the evaporation chamber itself. Heat for evaporation can beelectrical, natural gas, petroleum or other hydrocarbon fuels, or anysource of waste heat that provides a temperature of about 110 C orhigher.

In greater detail, the present disclosure relates to a waterpurification and desalination system comprising an inlet, a preheater, adegasser, a plurality of evaporation chambers, demisters, heat pipes,and product condensers, a waste outlet, multiple product outlets, aheating chamber, and a control system, wherein the heat of condensationis recovered and reused for additional evaporation, wherein distillationenergy may consist of electricity, the combustion of oil, hydrocarbons,or natural gas, or waste heat, and wherein the control system permitscontinuous operation of the purification and desalination withoutrequiring user intervention or cleaning, and wherein the system iscapable of removing, from a contaminated water sample, a plurality ofcontaminant types including: microbiological contaminants, radiologicalcontaminants, metals, salts, volatile organics, and non-volatileorganics; such that water purified in the system has levels of allcontaminant types below the levels shown in the MCL Column of Table 1,when the contaminated water has levels of the contaminant types that areup to 25 times greater than the levels shown in the MCL Column of Table1.

In a further aspect, the system produces a volume of purified water thatis between about 20% and about 95% of a volume of input water.

In a further aspect, the system does not require cleaning through atleast about two months of use.

In a further aspect, the system does not require cleaning through atleast about one year of use or longer.

In a further aspect, the system comprises an inlet switch to regulateflow of water through the inlet.

In a further aspect, the inlet switch comprises a mechanism selectedfrom the group consisting of a solenoid, a valve, and an aperture.

In a further aspect, the inlet switch is controlled by the controlsystem.

In a further aspect, the system comprises a shutdown control.

In a further aspect, the shutdown control is selected from the groupconsisting of a manual control, a flood control, a condenser capacitycontrol, and an evaporation chamber capacity control.

In a further aspect, the control system controls the inlet based uponfeedback from at least one of a temperature sensor in a evaporationchamber, a condenser float, and a flood detector.

In a further aspect, the control system controls the switch based uponfeedback from the purification system.

In a further aspect, the feedback is based upon at least onecharacteristic selected from the group consisting of: amount of water ina product water container, flow of product water through the productoutlet, time of water flow, time of no water flow, amount of water inthe evaporation chamber, detection of a leak, evaporation chamberpressure, output water quality (total dissolved solids), pressuredifferential across the evaporation chamber, and movement of wateracross an evaporation chamber overflow weir float.

In a further aspect, the system comprises a flow controller.

In a further aspect, the flow controller comprises a pressure regulator.

In a further aspect, the pressure regulator maintains water pressurebetween about 0 kPa and 250 kPa. (0 to 36 psi)

In a further aspect, the system comprises a sediment trap.

In a further aspect, water exiting the preheater has a temperature of atleast about 96° C.

In a further aspect, the degasser is in a substantially verticalorientation, having an upper end and a lower end.

In a further aspect, heated water from the preheater enters the degasserproximate to the upper end.

In a further aspect, heated water exits the degasser proximate to thelower end.

In a further aspect, steam from an evaporation chamber enters thedegasser proximate to the lower end.

In a further aspect, the steam exits the degasser proximate to the upperend.

In a further aspect, the degasser comprises a matrix adapted tofacilitate mixing of water and steam.

In a further aspect, the matrix comprises substantially sphericalparticles.

In a further aspect, the matrix comprises non-spherical particles.

In a further aspect, the matrix comprises particles having a sizeselected to permit uniform packing within the degasser.

In a further aspect, the matrix comprises particles of distinct sizes,wherein the particles are arranged in the degasser in a size gradient.

In a further aspect, water exiting the degasser is substantially free oforganics and volatile gasses.

In a further aspect, an evaporation chamber includes a plurality of heatpipes delivering heat that is transferred from a lower condenser.

In a further aspect, the evaporation chamber further comprises a drain,and wherein the drain is at or about the middle of the chamber.

In a further aspect, the evaporation chamber further comprising a selfcleaning medium comprising a plurality of particles enclosed within aconcentric perforated cylinder surrounding each heat pipe.

In a further aspect, an evaporation chamber comprises a self cleaningmedium for interfering with accumulation of precipitates at least in anarea proximate to the heat pipes in the evaporation chamber.

In a further aspect, the medium comprises a plurality of particles.

In a further aspect, the particles are substantially spherical.

In a further aspect, the particles comprise a characteristic permittingsubstantially continuous agitation of the particles by boiling of waterin the evaporation chamber.

In a further aspect, the characteristic is selected from the groupconsisting of specific gravity, size, morphology, population number andcomposition.

In a further aspect, the particles have a selected hardness, wherein thehardness permits scouring of the evaporation chamber by the particleswithout substantially eroding the particles or the evaporation chamber.

In a further aspect, the particles are composed of ceramic, metal,glass, or stone.

In a further aspect, the particles have a specific gravity greater thanabout 1.0 and less than about 8.0.

In a further aspect, the particles have a specific gravity between about2.0 and about 5.0.

In a further aspect, the heating chamber further comprising electricheating elements, gas or oil burners, or heat pipes that transfer heatfrom waste heat sources, and wherein the heating chamber is adjacent tothe bottom portion of the evaporation chamber.

In a further aspect, a demister is positioned proximate to an uppersurface of an evaporation chamber.

In a further aspect, steam from an evaporation chamber enters a demisterunder pressure.

In a further aspect, a demister is configured to produce a pressuredifferential, wherein the pressure differential is no less than 125 to2500 Pa.

In a further aspect, a demister is adapted to separate clean steam fromwaste steam via cyclonic action.

In a further aspect, an evaporation chamber prevents condensed dropletsfrom entering a demister by means of baffle guards and metal grooves.

In a further aspect, a ratio of clean steam to waste steam is greaterthan about 10:1.

In a further aspect, a steam quality comprises at least one qualityselected from the group consisting of: clean steam purity, ratio ofclean steam to waste steam, and total volume of clean steam.

In a further aspect, a demister control parameter comprises at least oneparameter selected from the group consisting of: a recess position of aclean steam outlet, a pressure differential across the demister, aresistance to flow of a steam inlet, and a resistance to flow of a steamoutlet.

In a further aspect, the system comprises heat pipes for cooling acondenser product.

In a further aspect, product water exits a product condenser through theproduct outlet.

In a further aspect, waste water exits the system through the wasteoutlet.

In a further aspect, the control system diverts product water to wastedrainage until the system reaches stable operating temperatures.

In a further embodiment, the present disclosure relates to a method ofpurifying and desalinating water, comprising the steps of: providing asource of inlet water comprising at least one contaminant in a firstconcentration; passing the inlet water through a preheater capable ofraising a temperature of the inlet water above 90° C.; stripping theinlet water of essentially all organics, volatiles, and gasses bycounterflowing the inlet water against an opposite directional flow of agas in a degasser; maintaining the water in an evaporation chamber foran average residence time of between 10 and 90 minutes, or longer underconditions permitting formation of steam; discharging steam from theevaporation chamber to a cyclone demister; separating clean steam fromcontaminant-containing waste in the demister such that yield of cleansteam is at least about 4 times greater than yield of waste from thedemister; condensing the clean steam to yield purified water, comprisingthe at least one contaminant in a second concentration, wherein thesecond concentration is lower than the first concentration; andrecovering and transferring heat from a condenser into an upperevaporation chamber or preheater, such that the amount of heat recoveredis at least 50% of the heat of condensation.

In a further aspect, the at least one contaminant comprises acontaminant selected from the group consisting of: microorganism,radionuclide, salt, and organic; and wherein the second concentration isnot more than a concentration shown in Table 3, and wherein the firstconcentration is at least about 10 times the second concentration.

In a further aspect, the first concentration is at least about 25-foldgreater than the second concentration.

In a further aspect, the gas is selected from the group consisting of:steam, air, and nitrogen.

In a further aspect, the process steps are repeated automatically for atleast about three months with no required cleaning or maintenance.

In a further aspect, the process steps are repeated automatically for atleast about one year with no required cleaning or maintenance.

In a further aspect, a stacked arrangement of the evaporation chambers,condensers, and preheater is enclosed in a metal shell, with perforatedplates that separate evaporation chambers and condensers.

In a further aspect, the perforated plates allow the passage of heatpipes, degassers, demisters, brine overflow tubes, and waste streamtubes.

In a further aspect, the materials of construction of evaporationchambers, preheaters, and heat pipes are made from a non-corrosivetitanium alloy

In a further aspect, the non-corrosive titanium alloy comprisesTi-6Al,4V alloy.

In a further aspect, the evaporation chambers, preheaters, and heatpipes comprise common steel or other metal or alloys coated withnon-corrosive chlorofluorocarbon polymers.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are front views of two embodiments of thedesalination/water purification system.

FIG. 2 is a schematic diagram of the bottom evaporation chamber.

FIG. 3 is an elevation view of the bottom evaporation chamber.

FIGS. 4 (a) through 4 (e) show possible heating configurations.

FIG. 5 is a schematic diagram of a condenser.

FIG. 6 is a plant view of a condenser.

FIGS. 7 A and 7B are schematic diagrams of a evaporation chamber fordouble and triple distillation configurations.

FIG. 8 is a schematic diagram of a condenser.

FIG. 9 is a schematic diagram of a preheater.

FIG. 10 is a plant view of a preheater.

FIG. 11 is an elevation view of a preheater.

FIG. 12 is a schematic diagram of a degasser.

FIG. 13 is an elevation view of a degasser.

FIG. 14 is a diagram of a baffle guard and a metal groove.

FIG. 15 is a picture of a baffle guard.

FIG. 16 is a schematic diagram of a cyclone demister.

FIG. 17 is a schematic diagram of a heat pipe.

FIG. 18 is a diagram illustrating the self-cleaning feature for a heatpipe.

FIG. 19 is an illustration of a possible configuration for attachingheat pipes to provide for leak-free operation.

FIG. 20 is a diagram of the control circuitry of an embodiment of thedesalination and water purification system.

FIG. 21 is an elevation view of an alternative embodiment for a stackedarrangement of a desalination system.

FIG. 22 is a diagram of a perforated plate for an alternative embodimentof a desalination system.

FIG. 23 is a plant view of an alternative embodiment for a stackedarrangement of a desalination system.

DETAILED DESCRIPTION

Embodiments of the invention are disclosed herein, in some cases inexemplary form or by reference to one or more Figures. However, any suchdisclosure of a particular embodiment is exemplary only, and is notindicative of the full scope of the invention.

Embodiments of the invention include systems, methods, and apparatus forwater purification and desalination. Preferred embodiments provide broadspectrum water purification that is fully automated and that does notrequire cleaning or user intervention over very long periods of time.For example, systems disclosed herein can run without user control orintervention for 2, 4, 6, 8, 10, or 12 months, or longer. In preferredembodiments, the systems can run automatically for 1, 2, 3, 4, 5, 6, 7,8, 9, 10, 11, 12, 13, 14, or 15 years, or more.

Embodiments of the invention thus provide a water purification anddesalination system including at least an inlet for saline water,contaminated water, or seawater, a preheater, a degasser, one or moreevaporation chambers, one or more demisters, one or more productcondensers with a product outlet, a waste outlet, and a control system,wherein product water exiting the outlet is substantially pure, andwherein a volume of product water produced is at least about 10, 15, or20% of a volume of input water, and wherein the control system permitsoperation of the purification system continuously without requiring userintervention. In preferred embodiments, the volume of product waterproduced is at least about 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75,80, 85, 90, 95, 96, 97, 98, or 99%, or more, of the volume of inputwater. Thus the system is of great benefit in conditions in which thereis relatively high expense or inconvenience associated with obtaininginlet water and/or disposing of wastewater. The system is significantlymore efficient in terms of its production of product water per unit ofinput water or wastewater, than many other systems.

Substantially pure water can be, in different embodiments, water thatmeets any of the following criteria: water purified to a purity, withrespect to any contaminant, that is at least 25, 30, 35, 40, 45, 50, 55,60, 65, 70, 75, 80, 85, 90, 95, 100, 125, 150, 175, 200, 250, 500, 750,1000, or more, times greater purity than the inlet water. In otherembodiments, substantially pure water is water that is purified to oneof the foregoing levels, with respect to a plurality of contaminantspresent in the inlet water. That is, in these embodiments, water purityor quality is a function of the concentration of an array of one or morecontaminants, and substantially pure water is water that has, forexample, a 25-fold or greater ratio between the concentration of thesecontaminants in the inlet water as compared to the concentration of thesame contaminants in the product water.

In other embodiments, water purity can be measured by conductivity,where ultrapure water has a conductivity typically less than about 0.1μSiemens/cm, and distilled water typically has a conductivity of about0.5. In such embodiments, conductivity of the product water is generallybetween about 0.1 and 0.77, typically between about 0.2 and 0.6,preferably between about 0.2 and 0.5, 0.2 and 0.4, or 0.2 and 0.3.Conductivity is a measure of total dissolved solids (TDS) and is a goodindicator of water purity with respect to salts, ions, minerals, and thelike.

Alternatively, water purity can be measured by various standards suchas, for example, current U.S. Environmental Protection Agency (EPA)standards as listed in Table 1 and Table 2, as well as other acceptedstandards as listed in Table 2. Accordingly, preferred embodiments ofthe invention are capable of reducing any of one or more contaminantsfrom a broad range of contaminants, including for example anycontaminant(s) listed in Table 1, wherein the final product water has alevel for such contaminant(s) at or below the level specified in thecolumn labeled “MCL” (maximum concentration level) where the inlet waterhas a level for such contaminant(s) that is up to about 25-fold greaterthan the specified MCL. Likewise, in some embodiments and for somecontaminants, systems of the invention can remove contaminants to MCLlevels when the inlet water has a 30-, 40-, 50-, 60-, 70-, 80-, 90-,100-, 150-, 250-, 500-, or 1000-fold or more; higher contamination thanthe MCL or the product water.

While the capacity of any system to remove contaminants from inlet wateris to some extent a function of the total impurity levels in the inletwater, systems of the invention are particularly well suited to remove aplurality of different contaminants, of widely different types, from asingle feed stream, producing water that is comparable to distilledwater and is in some cases comparable to ultrapure water. It should benoted that the “Challenge Water” column in Table 1 containsconcentration levels for contaminants in water used in EPA tests.Preferred embodiments of water purification systems of the inventiontypically can remove much greater amounts of initial contaminants thanthe amounts listed in this column. However, of course, contaminantlevels corresponding to those mentioned in the “Challenge Water” columnare likewise well within the scope of the capabilities of embodiments ofthe invention.

TABLE 1 Challenge Units Protocol MCL Water Metals Aluminum Ppm 0.2 0.6Antimony Ppm 0.006 0.1 Arsenic Ppm 0.01 0.1 Beryllium Ppm 0.004 0.1Boron Ppb 20 Chromium Ppm 0.1 0.1 Copper Ppm 1.3 1.3 Iron Ppm 0.3 8 LeadPpm 0.015 0.1 Mangancsc ppm 0.05 1 Mercury ppm 0.002 0.1 Molybdenum ppm0.01 Nickcl ppm 0.02 Silver ppm 0.1 0.2 Thallium ppm 0.002 0.01 Vanadiumppm 0.1 Zinc ppm 5 5 Subtotal of entire mix 36.84 Inorganic saltsBromide ppm 0.5 Chloride ppm 250 350 Cyanide ppm 0.2 0.4 Fluoride ppm 48 Nitrate, as N03 ppm 10 90 Nitrite, as N2 ppm 1 2 Sulfate ppm 250 350Subtotal of entire mix 800.9 Fourth Group: 2 Highly volatile VOCs + 2non-volatiles Heptachlor ppm EPA525.2 0.0004 0.04Tetrachloroethylene-PCE ppm EPA524.2 0.00006 0.02 Epichlorohydrin ppm0.07 0.2 Pcntachlorophcnol ppm EPA515.4 0.001 0.1 Subtotal of entire mix0.36 Fifth Group: 2 Highly volatile VOCs + 2 non-volatiles Carbontetrachloride ppm EPA524.2 0.005 0.01 m, p-Xylenes ppm EPA524.2 10 20Di(2-ethylhexyl) adipate ppm EPA525.2 0.4 0.8 Trichloro acetic acid ppmSM6251B 0.06 0.12 Subtotal of entire mix 21.29 Sixth Group: 3 Highlyvolatile VOCs + 3 non-volatiles 1,1-dichloroethylene ppm 0.007 0.15Ethylbcnzcnc ppm EP524.2 0.7 1.5 Aldrin ppm EPA505 0.005 0.1 Dalapon(2,2,-Dichloropropionic acid) ppm EPA515.4 0.2 0.4 Carbofuran (Furadan)ppm EPA531.2 0.04 0.1 2,4,5-TP (silvex) ppm EPA515.4 0.05 0.1 Subtotalof entire mix 2.35 Seventh Group: 3 Highly volatile VOCs + 3non-volatiles Trichloroethylene-TCE ppm EPA524.2 0.005 0.1 Toluene ppmEPA524.2 1 2 1,2,4 Trichlorobenzene ppm EPA524.2 0.07 0.15 2,4-D ppmEPA515.4 0.07 0.15 Alachlor (Alanex) ppm EPA 525.2 0.002 0.1 Simazineppm EPA525.2 0.004 0.1 Subtotal of entire mix 2.6 Eighth Group: 3 Highlyvolatile VOCs + 3 non-volatiles Vinylchloride (chloroethene) ppmEPA524.2 0.002 0.1 1,2-dichlorobenzene (1,2 DCB) ppm EPA524.2 0.6 1Chlorobenzene ppm EPA524.2 0.1 0.2 Atrazine ppm EPA 525.2 0.003 0.1Endothal ppm EPA548.1 0.01 0.2 Oxamyl (Vydate) ppm EPA531.2 0.2 0.4Subtotal of entire mix 2 Ninth Group: 3 Highly volatile VOCs + 3non-volatiles Styrene ppm EPA524.2 0.1 1 Benzene ppm EPA524.2 0.005 0.2Methoxychlor ppm EPA 525.2/505 0.04 0.1 Glyphosate ppm EPA547 0.7 1.5Pichloram ppm EPA515.4 0.5 1 1,3-dichlorobenzene (1,3 DCB) ppm EPA524.20.075 0.15 Subtotal of entire mix 3.95 Tenth Group: 3 Highly volatileVOCs + 3 non-volatiles 1,2-dichloropropane (DCP) ppm EPA524.2 0.005 0.1Chloroform ppm EPA524.2 80 0.1 Bromomethane (methyl bromide) ppmEPA524.2 0.1 PCB1242 Arochlor ppb EPA 505 0.5 1 Chlordane ppm EPA525.2/505 0.002 0.2 MEK—Methylehtylketone(2- ppb EPA524.2 0.2 Subtotalof entire mix 1.7 Eleventh Group: 4 volatile non-volatile PCBs 2,4-DDE(dichlorodiphenyl ppm EPA525.2 0.1 dichloroethylene)Bromodichloromethane ppb EPA524.2 80 0.1 1,1,1-Trichloroethane (TCA) ppmEPA524.2 0.2 0.4 Bromoform ppm EPA524.2 80 0.1 PCB 1221 Arochlor ppm EPA505 0.5 0.05 PCB 1260 Arochlor ppm EPA 505 0.5 0.05 PCB 1232 Arochlorppm EPA 505 0.5 0.05 PCB 1254 Arochlor ppm EPA 505 0.5 0.05 PCB 1016Arochlor ppm EPA 505 0.5 0.05 Subtotal of entire mix 0.95 Group No 12: 5volatile VOCs + 5 non-volatile PCBs dichloromethane (DCM) ppm EPA524.20.005 0.1 Methylenechloride 1,2-dichloroethane ppm 0.005 0.1 Lindane(gamma BHC) ppm EPA525.2 EPA 0.0002 0.05 Benzo(a) pyrene ppm 525.2 EPA0.0002 0.05 Endrin ppm 525.2/505 0.002 0.05 1,1,2-Trichloroethane (TCA)ppm EPA524.2 0.005 0.05 MTBE ppm EPA524.2 0.05 Ethylene dibromide--EDBppm EPA504.1 EPA 0.00005 0.05 Dinoseb ppm 515.4 0.007 0.05Di(2-ethylhexyl) phthalate (DEHP) ppm EPA525.2 0.006 0.05 Subtotal ofentire mix 0.5 Group No 13: Balance of 6 VOCs Chloromethane (methylchloride) ppm EPA524.2 0.1 Toxaphene ppm EPA 505 0.003 0.1trans-1,2-dichloroethylene ppm EPA524.2 0.1 0.2 Dibromochloromethane ppmEPA524.2 80 0.05 cis-1,2-dichlorocthylcnc ppm EPA524.2 EPA 0.07 0.051,2-Dibromo-3-Chloro propane ppm 504.1 0.0002 0.05

Determination of water purity and/or efficiency of purificationperformance can be based upon the ability of a system to remove a broadrange of contaminants. For many biological contaminants, the objectiveis to remove substantially all live contaminants. Table 2 listsadditional common contaminants of source water and standard protocolsfor testing levels of the contaminants. The protocols listed in Tables 1and 2, are publicly available at hypertext transfer protocolwww.epa.gov/safewater/mcl.html #mcls for common water contaminants;Methods for the Determination of Organic Compounds in Drinking Water,EPA/600/4-88-039, December 1988, Revised, July 1991. Methods 547, 550and 550.1 are in Methods for the Determination of Organic Compounds inDrinking Water—Supplement I, EPA/600-4-90-020, July 1990. Methods 548.1,549.1, 552.1 and 555 are in Methods for the Determination of OrganicCompounds in Drinking Water-Supplement II, EPA/600/R-92-129, August1992. Methods 502.2, 504.1, 505, 506, 507, 508, 508.1, 515.2, 524.2525.2, 531.1, 551.1 and 552.2 are in Methods for the Determination ofOrganic Compounds in Drinking Water Supplement III, EPA/600/R-95-131,August 1995. Method 1613 is titled “Tetra-through OctaChlorinatedDioxins and Furans by Isotope-Dilution HRGC/HRMS”, EPA/821-B-94-005,October 1994. Each of the foregoing is incorporated herein by referencein its entirety.

TABLE 2 Protocol 1 Metals & Inorganics Asbcstos EPA 100.2 Frcc CyanidcSM 4500CN-F Mctals - Al, Sb, Bc, B, Fc, Mn, Mo, Ni, EPA 200.7/200.8 Ag,Tl, V, Zn Anions - N0₃-N, NO₂—N, Cl, SO₄, EPA 300.0A TotalNitrate/Nitrite Bromide EPA 300.0/300.1 Turbidity EPA 180.1 2 OrganicsVolatile Organics - VOASDWA list + Nitrozbenzene EPA 524.2 EDB & DBCPEPA 504.1 Semivolatile Organics - ML525 list + EPTC EPA 525.2 Pesticidesand PCBs EPA 505 Herbicides - Regulated/Unregulated compounds EPA 515.4Carbamates EPA 531.2 Glyphosate EPA 547 Diquat EPA 549.2 Dioxin EPA1613b 1,4-Dioxane EPA 8270m NDMA - 2 ppt MRL EPA 1625 3 RadiologicalsGross Alpha & Beta EPA 900.0 Radium 226 EPA 903.1 Uranium EPA 200.8 4Disinfection By-Products THMs/HANs/HKs EPA 551.1 HAAs EPA 6251BAldehydes SM 6252m Chloral Hydrate EPA 551.1 Chloramines SM 4500Cyanogen Chloride EPA 524.2m

TABLE 3 Exemplary contaminants for system verification MCLG¹ 1 Metals &Inorganics Asbestos <7 MFL² Free Cyanide <0.2 ppm Metals - Al, Sb, Be,B, Fe, Mn, Mo, Ni, 0.0005 ppm Ag, Tl, V, Zn Anions - N0₃-N, NO₂—N, Cl,SO₄, <1 ppm Total Nitrate/Nitrite Turbidity <0.3 NTU 2 Organics VolatileOrganics - VOASDWA list + Nitrozbenzene EDB & DBCP 0 ppm SemivolatileOrganics - ML525 list + EPTC <0.001 ppm Pesticides and PCBs <0.2 ppbHerbicides - Regulated/Unregulated compounds <0.007 ppm Glyphosate <0.7ppm Diquat <0.02 ppm Dioxin 0 ppm 3 Radiologicals Gross Alpha & Beta <5pCi/1³ Radium 226 0 pCi/1³ Uranium <3 ppb 4 Disinfection By-ProductsChloramines 4 ppm Cyanogen Chloride 0.1 ppm 5 BiologicalsCryptosporidium 0⁴ Giardia Lamblia 0⁴ Total coliforms 0⁴ ¹MCLG = maximumconcentration limit guidance ²MFL = million fibers per liter ³pCi/l =pico Curies per liter ⁴Substantially no detectable biologicalcontaminants

Overall Description of Water Purification and Desalination System

In preferred embodiments, such as those shown in FIGS. 1A and 1B, thewater purification and desalination system consists of a verticallystacked arrangement of evaporation chambers (also known as boilers,boiling chambers, or boiling tanks) 1, 3 and 5 and condensers (alsoknown as condensing chambers) 2, 4 and 6 whereby a source of heat isprovided at the bottom of the stack, a preheater (also known as apreheating chamber) 7 is provided at the top of the stack, a degasser 8is provided at the top of the system to remove volatile organiccompounds from the incoming water, a plurality of demisters (also knownas demisting devices) 9 are provided to remove contaminated mistparticles from each evaporation chamber, a plurality of heat pipes 10are provided to recover heat from each condenser and transfer such heatto an upper evaporation chamber, and a waste stream outlet 11 isprovided to remove and drain water contaminants. Various alternativeconfigurations to the vertical stacked arrangement are possible to thoseskilled in the art, such as, for example, a lateral arrangement ofevaporation chambers, condensers, and preheater, and the like.

FIGS. 21, 22, and 23 illustrate an alternative embodiment of avertically stacked arrangement of evaporation chambers 1, 3 and 5 andcondensers 2, 4 and 6 whereby a source of heat is provided at the bottomof the stack, a preheater 7 is provided at the top of the stack, adegasser 8 is provided at the top of the system to remove volatileorganic compounds from the incoming water, a plurality of demisters 9are provided to remove contaminated mist particles from each evaporationchamber, a plurality of heat pipes 10 are provided to recover heat fromeach condenser and transfer such heat to an upper evaporation chamber,and a waste stream outlet 11 is provided to remove and drain watercontaminants. In such an alternative embodiment, all the evaporationchambers, condensers, and preheaters are encased in an outer shell 300,and the individual tanks are separated by plates, some of which areperforated plates 301 in order to accommodate the passage of heat pipes10, degasser 8, hot brine overflow tubes 21, waste stream tube 11, anddemisters 9. This alternative embodiment confers certain cost advantagesin manufacturing, and provides for a simpler configuration thatminimizes heat losses.

Incoming water containing contaminants, such as saline water orseawater, continuously enters the system at the top into a preheatertank 7. The volume of flow into the system is controlled by a flowcontroller, which can be a constant flow pump, a variable flow pump witha control valve, or various electronic control sensors that control theincoming flow pressure. In connection with the flow controller,optionally the flow controller can moderate water flow into the systemby varying pressure, and such pressure variations can be signaled bydetection within the system of greater demand for inlet water, and thelike. This variable control of flow, rather than binary control of flow,can permit capturing certain efficiencies in the system. Alternatively,the incoming flow volume into the system may be controlled by a signalreceived indicating that the system is capable of receiving additionalwater for the purification process. Such feedback of demand for moreinlet water can come from various points within the system including,for example, water level in the evaporation chamber(s) 1, 3 and 5, waterlevel in the product condenser(s) 2, 4 and 6, temperature of preheatedwater entering the degasser 8, temperature or volume of steam leavingthe evaporation chamber(s), and the like.

Other controls and feedback points can provide further benefit in theautomated function of the system including, for example, detection ofwater quality at any point in the system, detection of volume of wateror steam at any point in the system, detection of leaks or temperaturesthat are indicative of a system malfunction, and the like. Embodimentsof the system contemplate all such controls and combinations ofcontrols. These include, for example, controls detecting flooding,evaporation chamber capacity, and the like. In various embodiments,feedback can be qualitative and/or quantitative. These can include, forexample, the amount of water in a product condenser(s), flow of productwater through the product outlet, time of water flow, amount of water inthe evaporation chamber, detection of a leak, evaporation chamberpressure, output water quality (such as, for example, a measure of totaldissolved solids), pressure differential across the evaporation chamberor across other points in the system, flow of water across anevaporation chamber overflow, and the like.

Once heat energy is supplied either by electricity, natural gas or oilburners, or waste heat and the system is turned on, the system isconfigured for fully automatic control essentially throughout the lifeof the system. The system includes various feedback mechanisms to avoidflooding and to regulate water flow, pressure, output, and continuouscleaning, such that user intervention under normal circumstances is notrequired. Among these controls is a float level detector in thepreheater 7, a side float switch, a timer, temperature sensors, and apower meter.

Shut down controls include a manual control, a flood control which canbe a float or a moisture detector in the base of the system, a condensercapacity control and an evaporation chamber capacity control. Inaddition to controls that provide binary, on/off, switching of inletwater or other parameters, the system further contemplates variablecontrols such as, for example, pressure- or volume-based flow controls,pressure regulators, and the like. In preferred embodiments, a pressureregulator can regulate inlet water pressure so that it is between 0 and250 kPa, for example. In other embodiments, the pressure can be 10, 20,30, 40, 50, 75, 100, 125, 150, 175, 200, 225, 275, 300, 350, 400, 450,or 500 kPa, or more. Regulation of pressure, optionally in combinationwith regulation of other parameters, can attenuate volume and velocityof water flow in the system. For example, pressure regulation incombination with the dimensions of the system can provide water flowrates of between 2.5 and 132,000 liters/min, or more. Although thesystems described herein are primarily described in terms of relativelylarge scale water production, the system is scalable to any volume ofwater production. Accordingly there is no upper or lower limit to thevolume of water flow. Exemplary flow rates, however, include ranges of10 to 500 ml/min, 5 to 1,000 liters/min, 30 to 30,000 liter/min, 400 to200,000 liter/min, and the like.

The system can further include a sediment trap capable of removingsediments from inlet water, so as to avoid premature fouling of thesystem with such sediments. Various sorts of sediment traps are known inthe art, and can be selected for use with the systems of the invention.Likewise, to minimize user intervention and need for cleaning, asediment trap can itself have self-cleaning features. For example, asediment trap can have alternating sand filters, or revolving screens,wherein rotation from a fouled screen to a new screen can be driven by awater pressure differential across the device, such that when a screenreaches a certain saturation point in terms of accumulated sediments, itis switched for a screen that is not fouled by sediments. In someembodiments, a fouled screen or sand filter can be placed into a flowpath of water such that water flows across the sand filter or screen inan opposite direction from that of the original flow across the screen,thus dislodging sediments to a waste pathway or drain. Accordingly thesystems disclosed herein contemplate use of conventional as well asself-cleaning sediment traps.

The preheat function of the water purification and desalination systempreferably involves a preheater 7. However, this function can beperformed in numerous different ways, provided that the result is thatsaline water or seawater flowing into the system arrives at the degasser8 at a temperature of about 90° C. or more. Accordingly, the preheatfunction can be embodied in numerous different forms, including, forexample, a cylindrical tank, a rectangular tank, or differentconfigurations of any sort with a design permitting a high ratio ofsurface area to internal volume, and the like.

In preferred embodiments, such as illustrated by FIGS. 9, 10, and 11,the preheater is heated by a plurality of heat pipes 10 that penetratethe preheater through the bottom. These heat pipes transfer the heat ofcondensation from a condenser into the incoming seawater or salinewater. As seawater or saline water enters the preheater 7 throughorifice 71, the incoming water is gradually heated to near boilingtemperature by the heat pipes 10 as water flows in a spiral patternimposed by spiral vanes on the bottom of the preheater. As the incomingseawater or saline water reaches near boiling temperature close to theupper center of the preheater, it exits the preheater through tube 82and enters near the top of the degasser 8. The dimensions andconfiguration of the preheater are such as to allow for sufficientresidence time to elevate the temperature of the water in the preheaterto about 90° C. or more. Depending upon the scale of the system, and thecapacity of the system for throughput of water, the pre-heating functioncan benefit from materials and configurations that permit efficient heatexchange. Alternatively, in some embodiments, durability ofconstruction, space considerations, case of maintenance, availability orexpense of materials, as well as other considerations can affect thedesign choices in this aspect of the invention.

In some embodiments, the system can beneficially function undernonstandard environmental conditions such as, for example, highaltitude. At high altitudes, the boiling point of water, includingsaline water or seawater is less than 100° C., and thus with normalrates of application of heat to the evaporation chamber will generate agreater amount of steam and will permit a higher quantitative throughputin the system. In such embodiments, it is evident that preheattemperatures may also be affected. Given lower evaporation chambertemperatures and lower condenser temperatures, preheating to a desiredtemperature can be achieved by permitting longer residence time of waterin the preheater such as, for example, by configuring the preheater tohave a greater volume with an identical flow rate, or a lower flow ratewith an identical volume. However, due to elevated levels of steamgeneration in the evaporation chamber, in most embodiments, adjustingdownward the flow rate in the preheat tube to achieve beneficialresidence times and desirable preheat temperatures, would be disfavored.This is because the greater rate of steam generation implies aconcomitant higher demand for inlet water.

Degassing is accomplished by steam stripping as illustrated by FIGS. 12and 13. A key factor in degasser performance is mass transfer ratio: themass of water going downward in a vertical degasser as compared to themass of steam going upward. Indeed, degassing function can beaccomplished with various configurations that permit mass-transfercounterflow of water with a gas. In a preferred embodiment, the gas issteam; in others the gas can be air, nitrogen, and the like. Thevelocity and activity of mixing of water with steam is affected by thesize, conformation, and packing of the degasser column medium, as wellas the void volume between the particles of the medium. In preferredembodiments, the particles of the medium pack to form a spiral. Theperformance of the degasser is affected by the velocity and volume ofsteam and water passing therethrough; these can be controlled by suchfactors as the size of the steam inlet and outlet orifice, water flowrate, and the like. Useful information relating to degasser function anddesign is provided in Williams, Robert The Geometrical Foundation ofNatural Structure: A Source Book of Design, New York: Dover, 1979, whichis incorporated herein by reference in its entirety.

Control of inlet water flow rate, avoidance of large steam bubbles inthe degasser, and the like, can therefore aid efficient function of thedegasser. When these parameters are not within a desirable range,flooding or jetting can occur in the degasser. Flooding of inlet waterforms a water plug in the degasser and jetting shoots water out of thedegasser with the steam, either of which can interfere with degasserperformance. It is therefore desirable to operate in a zone thatminimizes flooding and jetting and that has a good balance between waterinflux and steam efflux. The degasser of embodiments of the presentinvention is particularly important in that it is not designed to removestrictly one contaminant as many conventional degassers are. Instead itremoves a variety of contaminants very effectively. In typical settings,where the inlet water has a contaminant at, for example, 1 ppm theprocess seeks to achieve reduction to 50, 40, 10, 5, 2, or 1 ppb.

Degassing water is normally achieved by heating the incoming water toincrease the vapor pressure of volatile compounds. At the boiling pointof each compound, the solubility of the dissolved gas drops to zero andthe gas will then exit the water. For example, many of the volatilesubstances found in drinking water are chlorinated compounds thatnormally have very large partial pressures at temperatures well belowthe boiling point of water. Thus, many of these substances can beremoved from water by heating the water to temperatures of about200-210° F. (93-99° C.) to effect proper degassing. However, thesubstances do not completely leave the water immediately; thus, it takessome period of time to completely remove the dissolved gases.

One difficulty with previous degasser designs is that they have littlecontrol of the residence time of the heated water in the degasser.Consequently, when excessive amounts of volatile substances are presentin the incoming water, there may not be sufficient residence timeprovided to effect degassing of all the volatile substances.Additionally, many degassers operate in the absence of pressurecontrols, which can lead to excessive loss of water vapor, when watervapor is the medium selected for effecting mass transfer of the volatilecomponents out of the system.

Another issue in degasser design is scalability. While large industrialdegassers operate with substantial pressure drops and large volumes ofboth liquid and gases that are effective for mass transfer and, thus,degassing, small degassers do not scale down well. What is needed is amore compact degasser that allows for additional residence time and thatis also capable of limiting the amount of wasted steam.

In some embodiments, a degasser is provided, which has concentric layersof particles, where an inner layer of particles is configured to resultin comparatively small spaces between the particles, and where an outerlayer of particles is configured to result in comparatively largerspaces between the particles. In various embodiments, the particlesexhibit random and structured packing in the degasser. The particles canbe made of a material such as, metal, glass, and plastic. The degassercan have a water entrance at the top. The degasser can have a wastesteam exit at the top, and have a heated steam entrance and water exitat the bottom.

In some embodiments, a degasser apparatus is provided that has acontainer that holds concentric layers of particles, where an innerlayer of particles is configured to result in small spaces between theparticles, where a middle layer of particles is configured to result inmedium spaces between the particles, and where an outer layer ofparticles is configured to result in larger spaces between theparticles. The medium spaces are such that water vapor in the systembegins to condense out of the gas phase, and the small spaces are smallenough that this process continues so that water vapor is transformedinto liquid water.

In other embodiments, the degasser container has a steam entrance at thebottom outer periphery of the container. The steam entrance allowsheating steam from a evaporation chamber to enter the container at theouter periphery and heat the outer periphery of the inside of thedegasser. The container has a steam exit at the top of the containerwhere waste steam exits the system. The container has a water entranceat the top of the container. The container has a purified water exit atthe bottom of the container. The water exit is located, for example, inthe center bottom of the container. The container is filled withparticles. There are, in some embodiments, three sizes of particles andeach particle of a given size is located in a concentric zone; thus, insuch embodiments, there are three concentric zones, each having aparticle of a given size. In a preferred embodiment, the particles areglass beads. In a more preferred embodiment, there are three sizes ofparticles with the largest sized particle in an outermost zone of thecontainer and the smallest sized particle in an innermost zone of thecontainer.

Some embodiments include a compact, more effective, degasser. Thedegasser preferably employs concentric layers of varying porosity sothat a zone is created in the degasser that allows steam to pass andanother zone is created that promotes water vapor condensation. Thedegasser includes particles inside the degasser that add surface area tothe inside of the degasser, thereby allowing for a greater residencetime for the water to be purified.

In some embodiments, the porosity of the system is achieved throughdifferently sized particles. In these embodiments, the particles in theouter layer have a relatively large size so that heating steam can morereadily pass from a source of steam, such as an evaporation chamber,into and throughout the degasser. This heating steam, coming from theevaporation chamber, can also act as an insulator to keep the insidetemperature of the system near the boiling point. Inside the outer layerof larger sized particles is a layer of medium sized particles. Thislayer of medium sized particles provides for adequate permeability andlong residence time, allowing for a higher percentage of the volatilesubstances to be degassed. This medium sized layer of pores andparticles is more likely to condense water from the steam, as there isless space between the particles. The inner layer includes smaller sizedparticles, so that the pores are mostly filled with degassed water,which flows, by gravity, into the evaporation chamber.

The degasser system is preferably located in close proximity to theevaporation chamber apparatus. Preferably, the degasser unit is locatedon the top of an evaporation chamber. This allows steam from theevaporation chamber to rise directly from the evaporation chamber intothe degasser. This also allows the degassed water from the degasser todrain straight into the evaporation chamber. As will be appreciated byone of skill in the art, there need not be any significant separationbetween the evaporation chamber and the degasser. In one embodiment,only a screen, to retain the particles, separates the degasser from theevaporation chamber.

The particles can be of any shape, for example, spherical,semi-spherical, amorphous, rectangular, oblong, square, rounded,polyhedral, irregular (such as gravel, for example), and the like. Theparticle surface can be varied as desired, such as, for example, solid,porous, semi-porous, coated, or structured to provide large residencetime, and the like. Preferably, the particles are spherical andnonporous. One of skill in the art will appreciate that the differentlysized particles will have differently sized spaces between them(interstitial spaces). For example, larger glass spheres will havelarger spaces than smaller glass spheres. The size of the interparticlespace can vary based on the size of the particles, the shape of theparticles, and other factors. As a general rule, generally sphericalparticles that are larger will also result in a mixture with largerporosity. That is, there will be relatively large spaces between thespheres. Likewise, particles that are smaller will have smallerinterstitial spaces, resulting in an environment that is more likely tocondense steam into liquid water.

The particles can be made of any suitable material. Exemplary materialsinclude but are not limited to metal, glass, composites, ceramics,plastics, stone, cellulosic materials, fibrous materials and the like. Amixture of materials can be used if desired. One of skill in the artwill be able to determine a suitable material for each specific purpose.Preferably, the material is made of glass. The chosen material willpreferable be capable of standing up to long term high temperature usewithout significant cracking, breaking, other damage, or leaching toxicmaterials into the water. If desired, the differently sized particlescan be made of different materials. For example, the outer particles canbe made of metal, the middle layer of temperature resistant plastic, andthe center layer of glass. The chosen material can preferably beresistant to breakage, rust, or cracking due to the heating process.

In some embodiments, rather than altering the size of the particles,other properties of the particles are altered, such as the surfaceproperties of the particles. Further, if desired, the degasser can bepacked with a mixture of differently sized particles, where the packingprocedure is performed so as to allow a progressively smaller particlesize to fill the center regions of the degasser. In some embodiments,the layers are packed with particles that are homogeneous throughout thelayer. In other embodiments, the layers are heterogeneous and cancontain other shaped beads, particles, glass wool, etc. Heterogeneity ofthe particles can include not only size but also, for example,composition, surface characteristics, density, specific heat,wettability (hydophobicity versus hydrophilicity), hardness, ductility,and the like. Preferably, as discussed above, the heterogeneity inwhatever form it takes is distributed in concentric rings within thedegasser, although other arrangements that are not concentric are alsocontemplated in some embodiments of the invention.

Examples of volatile contaminants that can be removed or lessened bytreatment of water with the method of the present invention include butare not limited to, methyl tertiary butyl ether, benzene, carbontetrachloride, chlorobenzene, o-dichlorobenzene, p-dichlorobenzene,1,1-dichloroethylene, cis-1,2-dichloroethylenetrans-1,2-dicholoroethylene, dichloromethane, 1,2-dichloroethane,1,2-dichloropropane, ethylbenzene, styrene, tetrachloroethylene,1,2,4-trichlorobenzene, 1,1,1,-trichloroethane, 1,1,2-trichloroethane,trichloroethylene, toluene, vinyl chloride, xylenes, natural gases, suchas oxygen, nitrogen, carbon dioxide, chlorine, bromine, fluorine, andhydrogen, other volatile organic compounds (VOCs), such as formic acid,ethyl hydrazine, methyl methacrylate, butyl ethyl amine, butanol,propanol, acetaldehyde, acetonitrile, butyl amine, ethyl amine, ethanol,methanol, acetone, allyl amine, allyl alcohol, methyl acetate, ammoniumhydroxide, and ammonia, and the like.

As illustrated by FIGS. 7A and 7B, once the incoming saline water orseawater has been degassed, it flows by gravity into a lower evaporationchamber 3. This boiling tank can be of essentially any size andconfiguration depending upon the desired throughput of the system andother design choices made based upon the factors affecting systemdesign. For example, the evaporation chamber can have a volume capacityof about 100 gallon or 2,000-10,000 gallons, 11,000-100,000 gallons, ormore. Because the system of the invention is completely scalable, thesize of the evaporation chamber is variable and can be selected asdesired. Likewise, the configuration of the evaporation chamber can bevaried as desired. For example, the evaporation chamber can becylindrical, spherical, rectangular, or any other shape. In a preferredembodiment, the evaporation chamber 3 is cylindrical, is perforated by aplurality of heat pipes 10 through the bottom of the evaporationchamber, has a centrally positioned discharge tube 21 that carriesexcess hot saline water down into a lower evaporation chamber, and has ademister 9 mounted on top of the evaporation chamber. In this preferredconfiguration, the waste stream 11 that carries volatile constituentsfrom the degasser top also traverses the evaporation chamber vertically.Clean steam 91 from the demister flows upward into an upper condenser 4.

Because the operation of the purification system is continuous, salinewater or seawater is partially concentrated by boiling, and the degreeof concentration in evaporation chamber 3 is determined by the number ofdistillation stages. Thus, if two stages of distillation are being used,the degree of salinity in the evaporation chamber is kept at half thevalue of the waste brine to be rejected, or about 12%. If three stagesof distillation are used, the degree of salinity in evaporation chamber3 is allowed to reach about one third of the final brine concentrationof about 23%.

In a preferred embodiment, the evaporation chamber drains by gravityonly, through drain tube 21. In other embodiments draining theevaporation chamber is driven by pumping action. Continuous draining ofthe evaporation chamber 3 maintains a constant level of boiling fluid inthe chamber, and such continuous drainage also avoids the settling ofsediments, salts, and other particulates in the evaporation chamber.

FIG. 18 illustrates the self-cleaning mechanism that prevents scaledeposition in the evaporation chamber. Scale tends to formpreferentially at the hotter surfaces which, in the case of evaporationchamber 3, correspond to the top surfaces of each heat pipe 10. In apreferred embodiment, the heat pipes are surrounded by a perforatedcylinder 27 and a plurality of ceramic balls 28. The self-cleaningmedium can be selected from any of a number of suitable alternatives.Such alternatives include glass or ceramic beads or balls, stones,synthetic structures of any of a variety of shapes, and the like. Inevery case, the properties of the self-cleaning medium will be selectedsuch that agitation by boiling water will displace individual particlesof the self-cleaning medium, but that such displacement will be overcomeby the physical properties of the self-cleaning medium causing eachparticle to fall again to the side of each heat pipe and to the bottomof the evaporation chamber, striking and dislodging any deposits orscale. For example, a self-cleaning medium with a relatively highspecific gravity but with a relatively small surface to volume ratio mayfunction in a way that is roughly comparable to a second self-cleaningmedium with a lower specific gravity but a relatively higher surface tovolume ratio. In each case, a skilled artisan is able to select thecombination of morphology, and composition to achieve the desiredresult. In some embodiments, an alternative approach to self-cleaning isemployed, such as, for example, application of ultrasonic energy.

Another consideration in the design choice of the self-cleaning mediumis the hardness thereof. In general, the hardness should be roughlycomparable to the hardness of the material of which the evaporationchamber is composed. This permits continued use of the self-cleaningmedium over long periods of time without significant erosion of themedium or of the walls or bottom of the evaporation chamber. In someembodiments, in which the heating element of the evaporation chamber isinternal to the chamber, such as the case with heat pipes 10, hardnessand other properties of the self-cleaning medium can be selected so asto avoid erosion and/or other damage to the heating element as well asto the evaporation chamber itself.

Because of the self-cleaning function provided by the structure of theevaporation chamber and the evaporation chamber cleaning medium, thesystem of embodiments of the invention does not require cleaning duringits normal life span of use. In some embodiments no cleaning is requiredfor 2, 3, 4, 5 or 6 months. In other embodiments, no cleaning isrequired for 9, 12, 18, 24, 30, or 36 months. In other embodiments, nocleaning is required for 4, 5, 6, 7, 8, 9, 10 years, or more.

The residence time of water in the evaporation chamber can vary within arange based upon the nature of the inlet water and the desiredperformance of the system. The suitable range is determined by variousfactors, including whether biological contaminants are in the inputwater. Effective removal of biological contaminants can require avariable amount of time being exposed to the high temperatures in theevaporation chamber. Some biological contaminants are more quicklysusceptible to high heat than are others. In many embodiments, aresidence time as short as 10 minutes is sufficient to kill mostbiological contaminants. In other embodiments, longer residence timesmay be desired in order to more thoroughly eliminate a broader spectrumof biological contaminants. The upper end of the range of residence timein the evaporation chamber is typically dictated by efficiencyconsiderations relating to the desired rate of generation of productwater in comparison with the energy required to maintain a selectedvolume of water at boiling temperature. Accordingly, residence time inthe evaporation chamber can be as little as the minimal time requiredfor water to reach boiling point and evolve as steam, to time pointsbeneficial to removal of biological contaminants such as, for example,10, 15, 20, 25, 30, 35, 40, 45 minutes and the like and so on. Further,higher residence times such as, for example, 50, 60, 70, 80 and 90minutes, or more, may be selected in some embodiments.

Steam produced in the evaporation chamber is generally free ofparticulates, sediments, and other contaminants. However, boiling actioncan cause certain contaminants to be carried into the vapor phase, forexample on the surface of microdroplets of mist formed at the air/waterinterface. In addition, steam can condense into droplets on theunderside of the evaporation chamber top, as illustrated in FIG. 14.Such droplets 14 can migrate laterally and can enter the demister device9 with the flow of steam. A metal groove 13 prevents such droplets frommigrating and contaminating the steam flow. In addition, a baffle guard15 may also provide a barrier to mist particles being carried by thesteam. FIG. 15 provides a picture of a baffle guard mounted on theunderside of a evaporation chamber.

In addition to the above steam cleaning mechanisms, clean steam can beseparated from such contaminant-laden mist with use of a demister.Various kinds of demisters are known in the known in the art, includingthose employing screens, baffles, and the like, to separate steam frommist based upon size and mobility. Preferred demisters are those thatemploy cyclonic action to separate steam from mist based upondifferential density. Cyclones work on the principle of moving a fluidor gas at high velocities in a radial motion, exerting centrifugal forceon the components of the fluid or gas. Conventional cyclones have aconical section that in some cases can aid in the angular acceleration.Key parameters controlling the efficiency of the cyclone separation arethe size of the steam inlet, the size of the two outlets, for cleansteam and for contaminant-laden mist, and the pressure differentialbetween the entry point and the outlet points.

As illustrated by FIGS. 3 and 16, the demister is typically positionedwithin or above the evaporation chamber 1 or 3, permitting steam fromthe chamber to enter the demister through an inlet orifice 92. Steamentering a demister through such an orifice has an initial velocity thatis primarily a function of the pressure differential between theevaporation chamber and the demister, and the configuration of theorifice. Typically, the pressure differential across the demister isabout 0.5 to 10 column inches of water—about 125 to 2500 Pa. The inletorifice is generally designed to not provide significant resistance toentry of steam into the cyclone. At high velocities, such as in thecyclone cone area 93, the clean steam, relatively much less dense thanthe mist, migrates toward the center of the cyclone, while the mistmoves toward the periphery. A clean steam outlet 91 positioned in thecenter of the cyclone provides an exit point for the clean steam, whilea mist outlet 94 positioned near the bottom of the cyclone permitsefflux of mist from the demister. Clean steam passes from the demisterto a condenser, while mist is directed to again enter the evaporationchamber. In typical operation, clean steam to mist ratios are at leastabout 2:1; more commonly 3:1, 4:1, 5:1, or 6:1; preferably 7:1, 8:1,9:1, or 10:1, and most preferably greater than 10:1. Demisterselectivity can be adjusted based upon several factors including, forexample, position and size of the clean steam exit opening, pressuredifferential across the demister, configuration and dimensions of thedemister, and the like. Further information regarding demister design isprovided in U.S. Provisional Patent Application No. 60/697,107 entitled,IMPROVED CYCLONE DEMISTER, filed Jul. 6, 2005, which is incorporatedherein by reference in its entirety. The demisters disclosed herein areextremely efficient in removal of submicron-level contaminants. Incontrast, demisters of other designs such as, for example, screen-typeand baffle-type demisters, are much less effective at removingsubmicron-level contaminants.

Clean steam is condensed in a condenser typically positioned directlyabove each evaporation chamber. Excess heat can be exhausted by a heatsink, a fan, a heat exchanger, or a heat pipe. In a preferredembodiment, heat is removed from the condenser by heat pipes, asillustrated by FIGS. 5, 6 and 8. A discussion of heat pipes fortransferring heat from condensing steam to inlet water is provided inU.S. Provisional Patent Application No. 60/727,106, entitledENERGY-EFFICIENT DISTILLATION SYSTEM, filed Oct. 14, 2005, and U.S.patent application Ser. No. 12/090,248, also entitled ENERGY-EFFICIENTDISTILLATION SYSTEM, filed Sep. 9, 2008 and published as U.S. PatentApplication Publication No. 2009/0218210, both of which are incorporatedherein by reference in their entirety.

Clean steam enters the condenser 2 or 4 or 6 via tube 91 from thedemister. As it enters the condenser, the steam rotates in a spiralfashion which increases residence time and render condensation mosteffective. The spiral motion of the steam in the condenser is effectedby spiral vanes. Heat of condensation is removed by a plurality of heatpipes 10, mounted on the upper surface of the condenser. As heat isremoved by the heat pipes and transferred upward to an upper evaporationchamber or preheater, steam condenses into product water that existsthrough a clean water outlet 24. Both waste steam tube 11 and the brineoverflow tube 21 that carries hot brine from an upper evaporationchamber to a lower one, traverse the condenser.

FIGS. 2 and 3 illustrate a preferred configuration of the bottomevaporation chamber and the heating system. Intermediate boiling andcondensers as may be employed in multiple distillation stages areentirely similar to those described above and are not repeated. Thebottom evaporation chamber 1 represents the last stage of salineconcentration by evaporation, and waste brine concentration from thisstage is at or below about 23% salt, so as to prevent crystallization atany point in the system. Hot saline brine enters the bottom evaporationchamber 1 through tube 21 which causes a hydraulic over-pressure ofseveral inches of water, or sufficient to maintain boiling temperaturesthat are 5-25 C higher than the topmost evaporation chamber, thusensuring efficient heat transfer between various distillation stages.Another tube placed inside the evaporation chamber and connected to thewaste drain stream 11 maintains a constant level of boiling brine in theevaporation chamber, and continuously removes waste brine and anyparticulates in suspension. Steam produced in the evaporation chamberenters demister 9 where it is cleaned.

Energy for distillation is provided by a heater tank 21 positioned atthe bottom of evaporation chamber 1. FIG. 4 illustrates variousdifferent configurations for providing heat. FIG. 4(a) illustrates thefact that the subject of this invention is energy agnostic. The proposedsystem for desalination can use any form of energy as energy source 211,including electricity, natural gas, oil or hydrocarbons, or even wasteheat sources, as long as they deliver heat at temperatures higher than120-130 C. FIG. 4(b) illustrates the simplest configuration, consistingof either an oil or a gas burner 212. FIG. 4(c) depicts an electricheater, provided with power supply 216 and resistive heater 213. FIG.4(d) illustrates resistive heating, using resistive heaters 213surrounded by an insulating sleeve 214 and connected to a power source216, of heat pipes 215 that subsequently transfer the heat into aevaporation chamber. And FIG. 4(e) illustrates the utilization of wasteheat 217 by using heat pipes 215.

FIG. 17 illustrates the principle of operation of conventional heatpipes. A heat pipe consists of a sealed tube 17 under partial vacuum,partially filled with a small volume of working fluid 18, whichtypically may be water, and also filled with a capillary wick 19. A heatsource 25 provides energy in the form of enthalpy to one end of the heatpipe, and that energy causes the evaporation of the working fluid 18.The vapor of the working fluid immediately fills the tube because it isunder partial vacuum. As soon as the working fluid vapor reaches theopposite end of the heat pipe, which is at slightly lower temperature,it condenses and provides the same enthalpy back in the from of heat ofcondensation. As the working fluid condenses into a liquid, it isadsorbed by the capillary wick which carries it back to the startingpoint. Because the heat of evaporation is, by definition, equal to theheat of condensation, a heat pipe transfers heat very efficientlywithout appreciable losses in temperature, other than heat lossesthrough the wall.

FIG. 19 illustrates a preferred configuration for attaching heat pipesto evaporation chamber 3 and condenser 2, so as to prevent leakage. Acircular sleeve 36 is either welded or otherwise attached to the heatpipe 10. A smaller diameter sleeve is welded or otherwise attached tothe evaporation chamber bottom 26 or the upper condenser top 37. Screws34 attach these sleeves under pressure so as to compress O-ring 33.

The materials of construction for the evaporation chambers andpreheaters can be any material that resists corrosion in salineenvironments. In a preferred embodiment, the evaporation chambers andpreheaters are manufactured using a titanium alloy, such as Ti-6Al-4V,which is known to resist corrosion of hot seawater. Alternatively,conventional carbon steel may be used when coated with specificchlorofluorocarbon polymers (e.g., Teflon®), or a variety of polymermaterials that resist boiling temperatures and saline environments.These materials of construction are exemplary and are not intended aslimitations on the scope of the invention. Those skilled in the art mayconsider alternative materials and coatings, such as other metals andalloys, which are encompassed within the spirit of the invention and aredefined by the scope of the disclosure.

In some embodiments, the system for purifying water, embodiments ofwhich are disclosed herein, can be combined with other systems anddevices to provide further beneficial features. For example, the systemcan be used in conjunction with any of the devices or methods disclosedin U.S. Provisional Patent Application No. 60/676,870 entitled, SOLARALIGNMENT DEVICE, filed May 2, 2005; U.S. Provisional Patent ApplicationNo. 60/697,104 entitled, VISUAL WATER FLOW INDICATOR, filed Jul. 6,2005; U.S. Provisional Patent Application No. 60/697,106 entitled,APPARATUS FOR RESTORING THE MINERAL CONTENT OF DRINKING WATER, filedJul. 6, 2005; U.S. Provisional Patent Application No. 60/697,107entitled, IMPROVED CYCLONE DEMISTER, filed Jul. 6, 2005; PCT ApplicationNo: US2004/039993, filed Dec. 1, 2004; PCT Application No:US2004/039991, filed Dec. 1, 2004; PCT Application No US06/40103, filedOct. 13, 2006, PCT Application No: US06/40553, filed Oct. 16, 2006; PCTApplication No. US2007/005270, filed Mar. 2, 2007, PCT Application No.US2008/003744, filed Mar. 21, 2008, and U.S. Provisional PatentApplication No. 60/526,580, filed Dec. 2, 2003; each of the foregoingapplications is hereby incorporated by reference in its entirety.

One skilled in the art will appreciate that these methods and devicesare and may be adapted to carry out the objects and obtain the ends andadvantages mentioned, as well as various other advantages and benefits.The methods, procedures, and devices described herein are presentlyrepresentative of preferred embodiments and are exemplary and are notintended as limitations on the scope of the invention. Changes thereinand other uses will occur to those skilled in the art which areencompassed within the spirit of the invention and are defined by thescope of the disclosure.

Control Instrumentation

This discussion is aided by reference to FIG. 20. When the main powerswitch is energized, the control circuitry determines start-upprocedures and, subsequently, continuous operation. Initially, power isdelivered to the intake pump that begins to feed water to the entiresystem at a constant flow rate. The user inputs include “start,”“pause/hold,” and maintenance mode, and the user status can show theoperating mode and sensor status either via a display, a remoteterminal, or via the Internet. A temperature sensor at the upperevaporation chamber detects temperatures lower than the boiling point ofwater and that activates a solenoid valve that diverts the output of allcondensers to a waste drain. The sensor inputs include one or more ofevaporation chamber temperature, degasser temperature, demistertemperature, inlet water turbidity (total dissolved solids), outletwater turbidity (total dissolved solids), and water overflow.Simultaneously, the same temperature sensor activates an energy inputswitch that activates energy input into the heater chamber. Depending onwhether the heater system operates with electricity, gas, oil, or wasteheat, the input switch turns on power to the electric coils, turns onfuel supply and ignites burners, or switches on a waste heat supply,respectively.

As the system comes up to temperature, the sensor in the upperevaporation chamber reaches boiling temperature, at which point itactivates a solenoid valve that closes the drainage of all condensersand allows the delivery of product water.

The control circuitry includes a number of safety features, all of whichturn power off the system while activating a warning light or audiblesignal. Conductivity sensors located at the product outlet continuouslymonitor water quality, and turn off the system if such qualitydeteriorates past a pre-determined point. Specifically, the operationstates include water quality alert, water quality error, and operatingmodes such as startup, normal, maintenance, and off; external systemcontrol may be enabled by source water flow or evaporation chamber heat.Similarly, a temperature sensor at the heating chamber preventsoverheating of the system. A conductivity probe located at the wastedrain stream measures the concentration of the waste brine and shuts offthe system if such concentration exceeds 23% salt so as to preventcrystallization problems inside the system. The desalination control canbe enabled by inlet flow control or by evaporation chamber drain.

It will be apparent to one skilled in the art that varying substitutionsand modifications can be made to the invention disclosed herein withoutdeparting from the scope and spirit of the invention.

Those skilled in the art recognize that the aspects and embodiments ofthe invention set forth herein can be practiced separate from each otheror in conjunction with each other. Therefore, combinations of separateembodiments are within the scope of the invention as disclosed herein.

All patents and publications are herein incorporated by reference to thesame extent as if each individual publication was specifically andindividually indicated to be incorporated by reference.

The invention illustratively described herein suitably can be practicedin the absence of any element or elements, limitation or limitationswhich is not specifically disclosed herein. The terms and expressionswhich have been employed are used as terms of description and not oflimitation, and there is no intention that in the use of such terms andexpressions indicates the exclusion of equivalents of the features shownand described or portions thereof. It is recognized that variousmodifications are possible within the scope of the invention disclosed.Thus, it should be understood that although the present invention hasbeen specifically disclosed by preferred embodiments and optionalfeatures, modification and variation of the concepts herein disclosedmay be resorted to by those skilled in the art, and that suchmodifications and variations are considered to be within the scope ofthis invention as defined by the disclosure.

1. A water purification and desalination system comprising an inlet, apreheater, a degasser, a plurality of evaporation chambers, demisters,heat pipes, and product condensers, a waste outlet, multiple productoutlets, a heating chamber, and a control system, wherein: the system isconfigured to recover the heat of condensation and reuse it foradditional evaporation; distillation energy is obtained from a sourceselected from the group consisting of electricity, combustion, and wasteheat, and said combustion is of a material selected from the groupconsisting of oil, hydrocarbons, and natural gas; the control system isconfigured to permit continuous operation of the purification anddesalination without requiring user intervention or cleaning; the systemis configured to be capable of removing, from a contaminated watersample, at least one contaminant type selected from the group consistingof microbiological contaminants, radiological contaminants, metals,salts, volatile organics, and non-volatile organics; and the system isconfigured such that water purified in the system has levels of allcontaminant types below the levels shown in the MCL Column of Table 1,when the contaminated water has levels of the contaminant types that areup to 25 times greater than the levels shown in the MCL Column ofTable
 1. 2.-64. (canceled)